Polishing Pad for Silicon Carbide Substrates
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Solution Overview
Problem
Polishing pads for silicon carbide substrates face challenges in minimizing scratches and undulation on the polished surface while maintaining a sufficient polishing rate, as existing pads either form scratches or undulation when trying to restrain them.
Innovation Solution
A polishing pad composed of polyurethane with abrasive grains, having a loss tangent of 0.1 to 0.35 and a glass transition temperature of 40° C. to 65° C., used in conjunction with a polishing method involving a disk-shaped polishing tool with a through-hole for supplying polishing liquid, effectively reduces scratches and undulation while maintaining a high polishing rate.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Object-affected harmful factors
If a polishing pad with fixed abrasive grains is used to restrain scratches, then undulation is formed in the polished surface
Solution Approach 1:
The patent applies parameter changes by precisely controlling the loss tangent (tan δ) to be 0.1 to 0.35 and the glass transition temperature (Tg) to be 40°C to 65°C of the polyurethane material. These specific parameter ranges enable the polishing pad to simultaneously reduce scratches and minimize undulation, resolving the technical contradiction between scratch prevention and surface flatness.
Solution Approach 2:
The patent uses a composite material system consisting of polyurethane as the base material with specific mechanical properties (controlled loss tangent and glass transition temperature) combined with abrasive grains. This composite structure allows the pad to provide both scratch reduction through controlled compliance and undulation reduction through appropriate hardness, resolving the contradiction between these two opposing requirements.
2Manufacturing precision
If the polishing pad is made softer to reduce undulation, then scratches increase on the polished surface
Solution Approach 1:
The patent resolves this contradiction by establishing specific parameter ranges: loss tangent of 0.1 to 0.35 and glass transition temperature of 40°C to 65°C. These parameters define an optimal balance point where the material is soft enough to reduce undulation but maintains sufficient structural integrity to prevent scratch formation, unlike simply making the pad softer.
3Manufacturing precision
If a polishing pad is used to reduce scratches and undulation, then polishing rate may fall below predetermined value
Solution Approach 1:
The patent resolves this contradiction by optimizing the loss tangent to 0.1 to 0.35 and glass transition temperature to 40°C to 65°C, which creates a material structure that maintains high polishing rate while achieving excellent surface quality. The specific parameter ranges ensure the pad remains sufficiently compliant for surface quality while maintaining adequate hardness for efficient material removal.
Solution Approach 2:
The patent applies dynamics by utilizing the viscoelastic properties of polyurethane within specific parameter ranges, allowing the material to dynamically adapt its effective hardness during polishing. The controlled loss tangent and glass transition temperature enable the pad to exhibit appropriate compliance for surface quality while maintaining structural integrity for polishing rate, resolving the contradiction between surface quality and productivity.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The described polishing pad and method achieve a reduction in scratches and undulation on the silicon carbide substrate while ensuring a polishing rate of not less than a predetermined value, making it suitable for polishing silicon carbide substrates.
Implementation Method 1
abrasive grains fixed by the polyurethane
Implementation Method 2
the polishing pad having a loss tangent (tan δ) represented by loss modulus (E′′)/storage modulus (E′) of 0.1 to 0.35 at 30° C. and a glass transition temperature of 40° C. to 65° C.
Data Source
AI summary
A polishing pad for polishing a silicon carbide substrate contains polyurethane and abrasive grains fixed by the polyurethane, and has a loss tangent (tan δ) represented by loss modulus (E″)/storage modulus (E′) of 0.1 to 0.35 at 30° C. and a glass transition temperature of 40° C. to 65° C. Also, a polishing method for polishing the silicon carbide substrate includes a holding step of holding a workpiece having the silicon carbide substrate by a chuck table and a polishing step of polishing the silicon carbide substrate by the polishing pad.